Polynuclear epoxide resin



United States Patent POLYNU CLEAR EPOXIDE RESIN Anthony Charles Davis, Solihull, Birmingham, and Robert Fergus Hunter, Olton, Birmingham, England, assignors to Bakelite Limited, London, England, a British company No Drawing. Filed May 18, 1956, Ser. No. 585,628

8 Claims. (Cl. 260-47) This invention is for improvements in or relating to epoxide resins and hasparticular reference to a new type of epoxide resin, the molecule of which contains a chain consisting of at least three phenylene groups linked by methylene groups.

It is known to prepare epoxide resins by reacting dihydric phenols with epichlorhydrin in the presence of a condensing agent, e.g. caustic soda. The dihydric phenols which may be used in the preparation of such epoxide resins may have phenolic hydroxyl groups attached either to the same benzene nucleus or to different benzene nuclei. The present invention is concerned with the preparation of epoxide resins from dihydric phenols in which the phenolic hydroxyl groups are attached to different benzene nuclei. Hitherto this specific type of We have now found that epoxide resins having improved flexibility, impact strength and adhesive properties coupled with a retention in cross-breaking strength and a lower volumetric shrinkage on curing, a lower exotherm and a long pot life when mixed with an amine hardener, can be made by reacting an excess of, e.g. epichlorhydrin, with polynuclear diphenols, which polynuclear diphenols contain at least three phenylene groups in a chain joined to one another by methylene groups and in which the phenolic hydroxyl groups are attached one on each terminal phenylene group.

According to the present invention there is provided a method for making an epoxide resin, which method consists of reacting with epichlorhydrin or a-dichlorhydrin a dihydric phenol containing at least three phenylene groups in a chain joined together by methylene groups in which the phenolic hydroxyl groups are attached one to each terminal phenylene group.

The simplest dihydric phenol used in this invention is bis-hydroxy benzyl-ben-zene, the molecule of which may be represented by the formula: I

The next one in the series of bis-hydroxybenzyl-diphenyl-meth'ane, the molecule of which may be represented by the formula:

dihydric phenol used to prepare epoxide resins has had the general formula: V

in which the hydroxyl groups may be in the 2,2; 2,3; 2,4; 3,3; 3,4; 4,4 positions on the aromatic rings which may bear other substituents and in which R and R separately may be hydrogen, lower alkyl, cycloalkyl, or substituted alkyl, phenyl, or substituted phenyl groups and in which R and R together with the connector carbon may be cyclohexylidene or alkyl cyclohexylidene or phenylene or an alkyl phenylene group.

The most commonly used diphenol is 4,4-dihydroxydiphenyl-dimethyl-methane known as his phenol A and this has the formula:

It is possible to react this diphenol with epichlorhydrin to give either a diglycidyl ether in which substantially the only reactive groups are epoxide groups or a diglycidyl either in which there are reactive epoxide and hydroxyl groups.

The low molecular weight diglycidyl ethers having substantially no reactive hydroxyl groups but only epoxide groups, may be formedby reacting a diphenol with a large excess of epichlorhydrin in the presence of a condensing agent, e.g. caustic soda, and the molecule of the resulting resin can be represented by the formula:

/ (IDES CH2.CH.CHzO-(|JOO.0112630112 on,

The nomenclature used in the present specification to denotethese compounds is based on that used by A. C; Davis, B. T. Hayes, and R. F. Hunter in Phenol-Formaldehyde and Allied Resins. II. Trinuclear and Hexanuclear Novolaks, Journal of Applied Chemistry, .1953, 3, pages 312-317 and by A. T. Carpenter and R. F. Hunter in Synthesis of 2:4:6-Trishydroxymethylphenol and of 2:4:6-Trishydroxybenzylphenol Derivatives, Journal of the Chemical Society, August 1954, (5004), pages 2731-2735.

Following is a description by way of example of methods of carryu'ng the invention into efiect.

Example 1 A trinuclear phenol was prepared by heating together p-bis-ehloromethyl-benzene (58 g.) and phenol (630 g.) at approximately 170 C. for one hour, and then boiling under reflux for 30 minutes. The excess of phenol was largely removed by distillation at reduced pressure and the last traces by distillation in steam. The semi-solid residue was dried by boiling with toluene (500 cc.) under and Demand Stark still head. The product (60 g.) which crystallized upon cooling was collected by filtration and dried in vacuum. The resulting 1,4-bis-hydroxybenzyl-benzene was a light brown crystalline powder, M.P. 150 to 156 C. An epoxide resin based on this phenol was then prepared by dissolving bis-hydroxybenzylbenzene (22 g.) in a mixture of epichlorhydrin (42 g.) and percent alcohol (11 g.). Sodium hydroxide (7.2 g.) in water (7 cc.) was added gradually with continuous stirring during four hours, the temperature being kept at 60 C. The alcohol and the excess of epichlorhydrin were removed by distillation at reduced pressure, and toluene (60 cc.) and water (30 cc.) were stirred into the residue. After separation from the aqueous layer, the toluene solution was concentrated in vacuum to leave the trinuclear resin (30.5 g.) as a viscous brown liquid solid mass. From the molecular weight and epoxide (n 1.5942) which slowly crystallized to a semi-solid content, the molecule of this resin can be represented by mass during storage. From the molecular weight and the formula:

o oH=oH-oHr-o-mm-cm-O-onQcm-mm-o-oarch- 0H:

epoxide content the molecule of this resin can be rep- The resin was warmed slightly to reduce the viscosity resented by the formula: and 9.9 percent by weight based on the weight of the oH,o11-0112-Q-QGm-OHFO-oH,-o6H,o-on,-orron,

The resin was warmed slightly to reduce its viscosity resin of diethylenetriamine was stirred in until a homoand 12.7 percent by weight based on the weight of the 0 geneous solution was formed. The mixture was poured resin of diethylenetriamine was stirred in until a homointo open molds and cured for 16 hours at 60 to 65 C. geneous solution was formed. The mixture was poured The modulus of the cured resin was 357 kg./sq. mm. into open molds and heat-cured for 16 hours at 60 to while the impact strength was 0.310 ft. lb., and the cross 65 C. The cured resin had a modulus of 387 kg./sq. breaking strength 21,600 psi. compared with 419 kg./sq. mm., an impact strength of 0.407 ft. lb. and across breakmm., 0.229 ft. lb., and 22,700 p.s.i. respectively for a ing strength of 21,200 p.s.i. The corresponding figures cured epoxide resin based on diphenylolpropane. Here for a cured epoxide resin based on diphenylolpropane again an epoxide resin of this invention, viz. that based were 419 kg./sq. mm. 0.229 ft. 1b., and 22,700 p.s.i. reon 4:4'-bis-hydroxybenzyldiphen-ylmethane had a signifispectively. Thus, it can be seen that the cured epoxide cantly higher impact strength than the resin based on resin based on 1:4-bis-hydroxy-benzylbenzene had a diphenylolpropane. significantly greater impact strength What we claim is:

Both resins were used to bond aluminum to aluminum 1. Diglycidyl ether of bis-hydroxybenzylbenzene havand, after curing the resinous bonds for 30 mins. at ing the formula:

115 C., the bond strength of the epoxide resin based on 2. 'Diglycidyl ether of 4,4-bis-hydroxybenzyl-diphenyll,4-bis-hydroxybenzylbenzene was 3,300 p.s.i. compared methane having the formula:

with 2,400 p.s.i. for the epoxide resin based on diphenylol- 3. A polyglycidyl ether of a dihydric phenol, said di-' propane. hydric phenol containing from three to four phenylene Example 2 groups in a chain joined to one another by single methyl- A tetranuclear phenol was first prepared by heating toem groups and in which ep enolic hydroxy groups gether at 100 C. 4,4'-bis-chloromethyl-diphenylmethane are attached one on each termmal phenylene g p- (70 g.) and phenol (600 g.) until evolution of hydrogen The Peat'cured Product of clalm 3, 531d Pmdlmt chloride slackened, and then boiling under reflux for 15 having an Impact Strength at least minutes. The excess of phenol was removed by concen- Producmg a Polyglycldyl ether uwhlch tration in vacuum followed by distillation in steam. The cqmpnses PP at a fifmpelfature P to a partially crystalline residue was freed from water by re- Imxture contmnmg dlhydnc Phenol f f f from fluxing in toluene (600 cc.) under a Dean and Stark still 60 three to foul: phenylene groups 111 ch31? lowed f head, and the solution was allowed to cool and the crysanother by Single methylene groups Whlch the P 9 talline product (72 g.) was filtered by suction and dried hydroxyl groups are attached one to each termmal in vacuum at 55 C. Anepoxide resin based on this phenylene group; a compoPnd selectefl from fp phenol was then prepared by dissolving consisting of eprchlorohydrin and a-dichlorohydrm, said benzybdiphenylmethane (41 in a mixture of 95 compound be ng present in an amount sufficient to recent ethanol (20 cc.) and epichlorhydrin (60 g.). The Place S ubstam1any an of hydroxyl groups 0f i 531d solution was stirred for 4% hours at 60 C. while a soludlhydnc Phenol Wlth glycldyl groups, and an alkali metal tion of sodium hydroxide (10 g.) in water (10 cc.) was compoundadded gradually. The alcohol and excess of epichlor- A method as defined claim 5 wherem the alka-h hydrin were removed by distillation at reduced pressure, metal compound is sodiufn hydfoxjdeand toluene cc.) and water (40 cc.) were stirred into Method as defined 3131111 5 Wherem the dlhydnc the residue. After separation from the aqueous layer, Phenol i5 ydr XYbenaylbenzene. I the toluene solution was concentrated in vacuum to leave Method as defined claim 5 wherem the dlhydrlc the tetranuclear resin (52 g.) as a viscous brown oil Phenol is -hy r xybenzyl diphenylmethane. (11 1.6082) which gradually crystalliz to an s 7 (References on following page) 5 6 References Cited in the file of this patent 2,716,099 Bradley et a1. Aug. 23, 1955 UNITED STATES PATENTS 11, Bader Oct- 2 1957 2,076,624 De Groote Apr. 13, 1937 FOREIGN PATENTS 2,142,007 Schlack Dec. 27, 1938 5 1,106,304 France July 20, 1955 2,543,489 De Groote et a1 Feb. 27, 1951 2,581,367 De Groote et a1 Jan. 8, 1952 OTHER REFERENCES 2,658,885 DAlelio Nov. 10, 1953 Carswell: Phenolplasts, Interscience Publishers, Inc.,

2,714,098 Martin July 26, 1955 New York, N.Y. (1947). 

1. DIGLYCIDYL ETHER OF BIS-HYDROXYBENZYLBENZENE HAVING THE FORMULA: 